1910] CURRENT LITERATURE 237 
tangential pitting of autumnal tracheids. The change in the living pines is 
seen in the disappearance of thick-walled ray cells, the presence of large com- 
pound ray pits, the development of ray tracheids, and the loss of tangential 
pitting of autumnal tracheids. The type of hard pines represented by P. 
resinosa in North America and P. silvestris in Europe i “the most highly 
developed and specialized condition among living pines.’ The nut pines (of 
North America and Asia) have piciform lateral ray pits and thick-walled ray 
cells, and in these features they are the living pines that approach most nearly 
to the cretaceous pines. The hard pines of the United States, with the excep- 
tion of P. resinosa, show a great range of variation from piciform to compound 
lateral ray pits; and the soft pines present a parallel series of gradations.— 
fe i BS 
Non-available water.—Bovir‘ has tested the effect of salts upon the non- 
available water in a soil of crushed quartz. Aside from a full nutrient solution 
of 0.2 per cent, various amounts of NaCl, ranging from 0.05 to 0.6 per cent, 
were added. To 100 grams of soil 20 grams of solutions were added. After 
the plants had grown considerably and the soil moisture was nearly exhausted, 
the cultures were placed in a special drying chamber of relative humidity of 
0.1. Soil was tested for contained moisture when the foliage began to wilt, 
and when it showed drying. The remaining water was essentially the same 
regardless of the amount of salt present. Assuming that none of the salts 
are absorbed by the plants, Bovie finds that the soil water, at the close of the 
experiments, in some cases would contain more than 300 per cent of salts, and 
that much of it must be in the solid form in spite of greatly increased solubility 
in the thin water films. He also offers some evidence for the movement of 
water in soils of low water content in the form of vapor, a thing already empha- | 
sized by various workers—WILLIAM CROCKER. 
ranspiration stream.—Z1JLsTRA‘ finds that lowering the temperature of 
sections (20 cm. in length) of stem of intact plants to 0° C. for several days, 
even under the most favorable conditions for transpiration, does not lead to 
wilting of the foliage. It is assumed that this renders the living cells of the 
zone comparatively inactive, without injuring them and without producing 
injurious or blocking material. The results are contrary to those obtained by 
the same method by Ursprunc, who used the results as an argument for the 
necessity of the activity of living cells to the continuity of the transpiration 
stream. Zij~strRa also conducted a number of experiments on the movement 
of o.r per cent Saureviolett (GrisBierR) in living and dead stems. He also 
goa ec y 
Bovie, Witu1am T., The effects of adding salts to the soil on the amount of 
nen-available water. Bull. Torr. Bot. Club 37:273-292. 1910. 
‘*Zijtstra, K., Contributions to the knowledge of the movement of water in 
ts. Reprint from Koninklijke Akad. Wetenschappen te Amsterdam. 1910:574- 
